This invention relates to an improved heat exchanger tube cleaning element capturing device.
It is known from the above-identified patents to connect individual elongated cleaning element capturing cages or baskets to both ends of longitudinally extending tubes disposed in a heat exchanger housing. The tube ends are held in position at both ends by transverse tube sheets. The baskets are adapted to contain shuttleable cleaning elements such as brushes. Fluid flowing in one direction through the tubes keeps the cleaning elements captured within their respective basket chambers, while the fluid discharges outwardly through openings in the basket walls. Upon reversal of fluid flow, the cleaning elements are forced out of their baskets and through the tubes to the baskets at the opposite tube ends to thereby perform a tube cleaning action.
Many baskets are designed of plastic and with their elongated body portions formed by alternating ribs and fluid flow-through slots which terminate in an annular outer end ring. The inner edge portion of the ring is alternately joined to the ribs or exposed to form the outer slot ends. For purposes of retaining a cleaning element within the basket and yet allowing the cleaning element to be removed for more complete access to the tube interiors, a retainer has been removably attached to the outer basket end. One form of retainer has comprised a central body supporting a plurality of flexible clip legs which extend longitudinally inwardly. The clip legs are provided with end prongs and stop projections spaced therefrom. When the retainer is assembled onto the basket, the prongs snap into the slots and the stop projections engage the outer edge of the basket end ring to limit entry of the retainer into the basket.
Heretofore, the relative width of the basket slots and prongs has been such that the retainer was free to rotate a distance limited by the width of the slots. It has been found that operation of the heat exchanger over a period of time with pressurized fluid impinging on the basket assembly has caused the stop projections to cut or dig into the basket ring edge to the point where the ring was either substantially weakened or broken through. This phenomenon is believed to be due to vibrations of the retainer caused by the fluid flowing at high velocity, said vibrations causing the retainer to oscillatingly rotate back and forth.
It is an object of the present invention to eliminate the undesirable damage to the basket by the retainer.
In accordance with the various aspects of the invention, means are provided to hold the retainer in a fixed annular position so that a clip leg cannot oscillate between slot edges during operation of the system, thus eliminating the wearing of the basket ring by the retainer. In the present embodiment, at least one outer slot end is provided with a longitudinally inwardly extending stepped portion forming, with one slot edge, a narrow notch within which the retainer prong is confined so that it cannot rotate.